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When two objects interact, what can you say about the forces they exert?
They are equal and opposite
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What effect will alcohol and other drugs have on braking distance?
None.
They will only affect thinking distance (which will affect stopping distance)
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Name two ways to increase a vehicles top speed
- Reduce air resistance (by making it aerodynamic)
- Increase its power (to increase the thrust driving it forward)
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At which stage of this graph is the object travelling at it's terminal velocity? 
- c) or e)
- c is terminal velocity before opening the parachute, e) is after opening it
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When an object is travelling at its terminal velocity, what do you know about the forces acting on it?
They are balanced (equal and opposite)
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What is a resultant force?
A single force that represents the result of adding together several other forces
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What is the resultant force in this case?
 - The length and direction of the force arrow is important
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If the resultant force acting on a stationary object is zero, what will happen to the object?
It will stay stationary
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If the resultant force acting on a stationary object is not zero, what will happen to the object?
It will accelerate in the direction of the resultant force
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If the resultant force acting on a moving object is zero, what will happen to the object?
It will continue to move at the same speed and in the same direction
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If the resultant force acting on a moving object is not zero, what will happen to the object?
The object will accelerate in the direction of the resultant force
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What two factors affect the acceleration of an object?
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What does the gradient of a distance-time graph represent?
Speed
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What is the speed of the object shown in the first section of this distance-time graph?
- 5 m/s
- (It travels 10 meters in 2 seconds)
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What is the difference between speed and velocity?
- Speed just has a size
- Velocity has a size and a direction (a vector)
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What does acceleration mean?
How quickly the velocity of an object changes
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What does the gradient of a velocity-time graph represent?
- acceleration
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How can you calculate distance travelled from a velocity-time graph?
- Calculate the area under the graph
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When a vehicle is travelling along a road, which forces resist its movement and which is the biggest?
- Air resistance (biggest)
- Friction
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What is the relationship between
stopping, braking and thinking distances?
- Stopping distance = thinking distance + braking distance
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What does thinking distance mean?
The distance you travel whilst your brain is thinking about applying the brakes
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Name three things that can affect a driver's thinking distance?
- Tiredness
- Alcohol / other drugs
- Distraction (eg on telephone, fiddling with radio)
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When vehicle brakes are applied and the vehicle loses kinetic energy, where does the energy go?
Friction between the brakes and the wheel increases the temperature of the brakes
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Name three things that can affect a vehicle's braking distance
- Adverse weather conditions (wet or icy)
- Poor condition of vehicle (brakes & tyres only - not whether it is dirty/ rusty/ the winscreen wiper don't work!)
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When a body moves through a fluid (liquid or gas), how does speed affect the frictional force on it?
The frictional force (eg air resistance) increases as the speed increases
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Why does a parachute reduce a skydiver's terminal velocity?
- When the parachute is open, the air resistance is greater.
- This air resistance will match the weight of the parachutist at a slower speed than if the parachute were not used.
- (At terminal velocity, air resistance = weight)
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What is the relationship between weight, mass and the gravitational field strength (g)?
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What is the name and symbol for the units of force ?
Newtons (N)
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What is the name and symbol for the unit of mass ?
- Kilogram (kg)
- NOT grammes (g)
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When a force changes the shape of an elastic object, in what form is the energy stored inside the object?
Elastic potential energy
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